Corrosion of Paint
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Application methods vary from the traditional paint brush or roller to various spray techniques, powder coating, and electrodeposition. Exact procedures will depend on the specific coating used and the object to be coated.
7.7.1.1 Brushing
Brushing is an effective, relatively simple method of paint application, particularly with primers, because of the ability to work the paint into pores
and surface irregularities. Because brushing is slow, it is used primarily for
smaller jobs, surfaces with complex configurations (edges, corners, cuts, etc.),
or where overspray might cause a serious problem.
Brushing was once the main coating method but, at the present, spray coating is more widely used. Brush coating has the following advantages:
1. Applicators are simple and inexpensive.
2. Complicated forms and shapes can be coated.
3. Thick films are obtained with one coat.
4. Particularly useful in applying an anti-rust coating.
The disadvantage of brushing results from the nonuniformity of coating layers, especially coating layers of rapidly drying paints.
7.7.1.2 Rolling
The advantage of using rollers is found when used on large, flat areas that
do not require the smoothness or uniformity that can be obtained by spraying. They are also used in interior areas, where overspray presents a cleaning and masking problem. Because of the difficulty of penetrating pores,
cracks, and other surface irregularities, the use of a brush is preferred when
applying primers. When using a roller, air mixes with the paint and leaves
points where moisture can penetrate the cured film. Rolling is best when
used to apply a topcoat over a primer that has been applied by some other
method.
7.7.1.3 Roller Coating
Roller coating is a process to coat coils and sheets by passing them through
two preset rollers. The quantity of paint consumed is reduced by approximately 50% of that used with other coating methods. The thickness of the
film is controlled by adjusting the rollers. One-side or both-side coatings are
possible.
231
Application methods vary from the traditional paint brush or roller to various spray techniques, powder coating, and electrodeposition. Exact procedures will depend on the specific coating used and the object to be coated.
7.7.1.1 Brushing
Brushing is an effective, relatively simple method of paint application, particularly with primers, because of the ability to work the paint into pores
and surface irregularities. Because brushing is slow, it is used primarily for
smaller jobs, surfaces with complex configurations (edges, corners, cuts, etc.),
or where overspray might cause a serious problem.
Brushing was once the main coating method but, at the present, spray coating is more widely used. Brush coating has the following advantages:
1. Applicators are simple and inexpensive.
2. Complicated forms and shapes can be coated.
3. Thick films are obtained with one coat.
4. Particularly useful in applying an anti-rust coating.
The disadvantage of brushing results from the nonuniformity of coating layers, especially coating layers of rapidly drying paints.
7.7.1.2 Rolling
The advantage of using rollers is found when used on large, flat areas that
do not require the smoothness or uniformity that can be obtained by spraying. They are also used in interior areas, where overspray presents a cleaning and masking problem. Because of the difficulty of penetrating pores,
cracks, and other surface irregularities, the use of a brush is preferred when
applying primers. When using a roller, air mixes with the paint and leaves
points where moisture can penetrate the cured film. Rolling is best when
used to apply a topcoat over a primer that has been applied by some other
method.
7.7.1.3 Roller Coating
Roller coating is a process to coat coils and sheets by passing them through
two preset rollers. The quantity of paint consumed is reduced by approximately 50% of that used with other coating methods. The thickness of the
film is controlled by adjusting the rollers. One-side or both-side coatings are
possible.